The horrors of Haiti's earthquake continue to unfold. The quake itself killed perhaps 100,000 people. The inability to organise rapid relief is killing tens of thousands more. More than one million people are exposed to hunger and disease and, with the rain and hurricane seasons approaching, are vulnerable to further hazards.

Even an economy as impoverished as Haiti's is a complex system dependent on trade between rural and urban areas, transport, electricity, port services, and government functions. Haiti's economy worked badly in the past, and was still reeling from four hurricanes in 2008 when the earthquake struck.

The fact that the quake hit the capital, and demolished every centre of social activity, destroyed the systems upon which daily urban life depends. Millions of people are now without livelihoods and the means for survival.

The first stage in an effective response, the first three or four weeks, must focus on rescuing survivors and stabilising supplies of food, water, medical services, and shelter for the population. Neither Haiti nor the world was properly equipped for this, and tens of thousands will die needlessly. The world's emergency response systems – especially for impoverished countries in zones that are vulnerable to earthquakes, volcanoes, droughts, hurricanes, and floods – needs upgrading.

After just a month or so, the emergency phase will give way to a decades-long struggle for recovery and long-term development. Haiti must avoid a prolonged period of tent cities in which people are mere refugees. But where should displaced people – numbering hundreds of thousands, and perhaps more than a million – live? How should they be provided with food, water, healthcare, and shelter? And how can they begin to contribute to the revival of basic economic life?

The economy will have a simple structure in the coming years, with most economic activities focused in five sectors: smallholder, or peasant, agriculture; reconstruction; port services and light manufacturing; local small-scale trade; and public services, including healthcare and education. The key challenge is to support these five sectors in order to combine short-term relief with long-term reconstruction and development.

First, special efforts should be made to boost peasant agriculture and rural communities. This will enable hundreds of thousands of displaced people to return to their village communities and live from farming. With fertiliser, improved seeds, small-scale irrigation, rapid training and extension services, and low-cost storage silos, Haiti's food production could double or triple in the next few years, sustaining the country and building a new rural economy.

Reconstruction – of roads, buildings, and water and sanitation systems – will employ tens of thousands, perhaps hundreds of thousands, of Haitian construction workers, and boost the regeneration of towns. The World Food Programme can help peasant farmers to produce more food in the countryside and then purchase the food to use in food-for-work programmes oriented to construction projects.

Haiti's infrastructure was meager before the earthquake (hence the shocking mortality rate), and most of that is now rubble. Large-scale capital investment will also be needed to re-equip the ports and to re-establish a power grid.

Recovery will also require re-establishing at least a small-scale manufacturing sector. Haiti, like its next-door neighbour, the Dominican Republic, once created jobs in port facilities, including production of clothing, baseballs, and other light manufacturing items. Those jobs disappeared in the 1990s, when the US imposed a trade embargo on Haiti as part of an effort to re-establish democracy. Democracy returned, but the economy was destroyed.

Other countries have risen from the rubble of natural disaster and war, and Haiti can do the same over the next five to 10 years. For the next decade, however, and especially for the next five years, there will be no escape from the need to rely on international financing, and mainly grant assistance, to finance the rebuilding effort. The world has spent heavily in Haiti before, but very ineffectively. This time, it must be done right.

A clear strategy is needed to bolster the key sectors discussed above. Each sector requires a five-year recovery strategy with a clear budget and clear lines of partnership and responsibility linking the Haitian government, non-governmental organisations, and institutional donors, especially governments and international agencies.

The second key to successful reconstruction is to harmonise the international response. There are probably 40 or more official organisations from abroad, if not more, already engaged in the recovery effort. In addition, there are hundreds, if not thousands, of native Haitian NGOs. The Haitian government itself has been reduced to paralysis by death and destruction.

There should be one overarching framework. There should be one major multi-donor bank account to finance the heavy outlays required for Haiti's recovery. There should be a highly professional executive team co-ordinating the international support efforts. And all of this should be put in place very soon, while there is international interest. The world will move on to the next crisis very soon, well before Haiti has even started to recover.

I have watched the problems of international co-operation for a quarter-century. Each agency has its role, but they also tend to squabble over turf rather than co-operate. International financial promises are made for headlines and photo opportunities, but end up undelivered. We therefore need money in the bank, and clear leadership.

My nominee to guide the process is the Inter-American Development Bank. The IDB's deep, long-term commitments in Haiti and professional expertise in agriculture, health, education, and infrastructure qualify it to co-ordinate the multitude of agencies that will be involved. It should work closely with a professional executive team made up of native and diaspora Haitian professionals with relevant expertise.

Rebuilding Haiti will cost perhaps $10-$20bn, and will take much of the coming decade. Getting started now will save countless lives and prevent a further tragic downward spiral of a society that stands on the brink of survival.